290 move rule-Fritz 12

One night I played Fritz...thinking it was smart.

I was astounded. What the heck is the 290 move rule? I'm sure some people here have tried to play out the longest game possible without any threefold repetition and then making a pawn move at the final move. if 16 pawn moves for every side... that would be ~16*50=900 moves. then there would be a capture-8 captures. 8*50=400, and so on..

I had reached 290 moves and Fritz suddenly claimed a 290 move draw. It said "Draw by 290 move rule."

I've tried researching what it is, but all I get is a 290 move puzzle.

Could it be engine space...or something irrelevant to chess.

If any of you have tried this... and experienced the same thing please let me know.

Or if anyone knows or comes up with some info about it.

I know that already...I want to know if anyone can give me more info on the 290 move rule.